Client need some way to get the session expiration timeout

[magodo]

As we know, the timeou passed to zk.Connect() is not necessarily to be the final one. Hence the client should have some way to tell the final timeout after authenticating between server.

This timeout value is necessary when zk is used to implement lock. In this case, when client holding the lock disconnect, it should behave conservatively to try to stop all the outstanding tasks before client expires. If client couldn't guarantee this, then it should just quit (so as to avoid brain split).

[msolo]

The session timeout is internally reset on connect. Unfortunately, accessing this private variable results in data races. It is fixed in our fork:

https://github.com/z-division/go-zookeeper/blob/master/zk/conn.go#L407

That could be exposed publicly which would match the Java client, but it is not something we have found broadly useful.